On 2024-12-18 13:46, microsuxxor wrote: > try > > p=$$ ; while sleep 1 ; do kill -USR1 "$p" ; done &
That's not necessary; my existing repro steps successfully show a difference between two signals, that being the only difference between them. The $$ parameter is expanded to a decimal numeric word *before* the while command is executed, so the background process is referencing the correct PID of the parent. There is no need to smuggle the PID through a variable. $$ in the while command will not refer to the child process' (That would be an issue if we had used eval: eval 'command ... $$ ...' & now we backgrounded the eval, which then in the background process parses the shell syntax and does all the expanding. Now $$ is the PID of the background process, not that of the shell which launched it.) > try also trap - USR1 in the new process ( the while loop ) We don't want that at all. The new process is just a helper to generate the signal to our main process. It doesn't receive the signal itself.
